Prognostic components of the nonreactive nonstress test.

From January 1976 to November 1978, 2592 nonstress tests were performed at the authors' institution on 862 fetuses, of which 2239 (86.3%) had reactive and 353 (13.6%) had nonreactive results. Of these 862 fetuses, 842 were delivered at the authors' hospital. Of these 842 fetuses, 109 were delivered within 1 week of a nonreactive tracing and 733 were delivered within 1 week of a reactive tracing. A retrospective analysis was performed on 102 of the nonreative tracings done within 1 week of delivery to assess the significance of various components of the nonstress test on the subsequent stress test and perinatal outcome. No significant difference could be observed in the number of fetal movements and total number of accelerations as compared with the subsequent stress test. However, the nonreactive tracings of the contraction stress test (CST)-positive group differed from those of the CST-negative groups in number of accelerations over 15 beats per minute (38% versus 48%) (P < .05) and in the number of accelerations lasting longer than 20 seconds (20% versus 50%) (P < .01). The number of nonreactive fetal movements per test (2.6 versus 0.96) (P < .05) and the percentage of nonreactive fetal movements (33% versus 15%) (P < .01) were different in both groups. The growth-retarded fetus in the nonreactive group did not differ in the number of fetal movements or total accelertions when compared to fetuses born appropriate for gestational age, but the number of accelerations was more than 15 beats per minute (26% versus 50%) (P < .01) and the number of accelerations lasting 20 seconds (11% versus 28%) (P < .01) did differ significantly.